Facebook owns PII data -- data the user attests -- and user engagement data. Snapchat just has user engagement data -- data derived from the user's behavior. This is a notable difference, but frankly, at this point in time it doesn't matter: every potential advertiser worth their salt knows that the average Snapchat user is between 14-25. Both services usually know location.

To many advertisers, the Facebook ad platform's sophisticated audience analysis isn't so much value-add as a way to prune people unlikely to be interested from being shown your ads. This is why the comparisons between Snapchat and MTV are apt.

Profile information can be useful for the platform itself, since they can use it to target specific ads to people who are most likely to engage with them (watch video, click through or do something else). Since there is only limited space for ads available, being successful with this might be quite important.